"This is an important step toward addressing not just the NTSB safety recommendation, but toward improving overall safety in the Metrorail system," said WMATA General Manager and Chief Executive Officer Paul Wiedefeld in a press release. "The sealing sleeves help protect the power cables from the intrusion of water and contaminants that may cause electrical damage."

NTSB investigators found that some electrical connections associated with the power supply to the third rail were improperly built and mounted, which could allow moisture to enter the components, WMATA officials said.

Since there are hundreds of these kinds of connections throughout the system, the agency initially prioritized installation locations based on water intrusion conditions. WMATA also created a three-year project timeline.

At the direction of Wiedefeld, the agency accelerated work following an early morning tunnel fire at the McPherson Square in March. The incident also led to the unprecedented 29-hour closure of WMATA's Metrorail system for emergency inspections of the system's third-rail power cables.

Installation of weather-tight seals on all above-ground third-rail power feeds and jumpers will be completed by the end of the summer, WMATA officials said.

The D.C.-area transit agency has been working to improve the safety and reliability of its subway system since a fatal smoke incident near the L'Enfant Plaza Station in January 2015. To read more about WMATA's attempts to bolster safety, read this article in the June issue of Progressive Railroading.